The objective of this proposal is to utilize mouse monoclonal antibodies to HTLV-III to evaluate the feasibility of detecting HTLV antigen expression on T lymphocytes in clinical specimens from patients with lyphadenopathy syndrome and overt AIDS, and in individuals in high risk groups, by: a) producing an array of mouse monoclonals to HTLV-III antigens by immunizing with selected antigens in extensive immunization protocols; b) selecting hybrid cultures reactive to HTLV-III by ELISA screening and Western Blotting and to clone and characterize hybrids which express selective reactivity patterns to HTLV-III; c) to evaluate selected monoclonal antibodies for use in detecting HTLV-III antigen expression on human T lymphocytes by flow cytometry; and d) to use selected monoclonal antibodies in a retrospective trial to compare i) ELISA reactivity, ii) Western Blotting, iii) T lymphocyte H/S ratio, and iv) HTLV antigen expression by flow cytometry on a bank of selected samples.